Former Illinois Republican Chairman Andy McKenna is expected to announce he's running for governor, with state Sen. Matt Murphy of Palatine giving up his bid for the post to serve as his running mate, sources familiar with the partnership said Wednesday.

McKenna's move comes almost a month after his surprise announcement on Republican Day at the Illinois State Fair that he was giving up the party chairmanship he held for four years. McKenna said leaving that volunteer post would give him "the freedom to be involved in primaries," though he did not discuss a potential primary run for governor at that time.

McKenna, a Chicago businessman who long lived on the North Shore, passed this summer on a U.S. Senate run to back North Shore Republican U.S. Rep. Mark Kirk.